Copying or enlarging camera.



J. BECKER.

COPYING 0R ENLARGING CAMERA.

APPLICATION FILED NOV. 3, 1914.

1,126,352, Patented Jan.26, 1915. 4 SHEETSSHEET 1.

- [ms enrol" J. BECKER. COPYING OR ENLARGING CAMERA. APPLICATION FILEDNOV. 3, 1914.

1,126,352. Patented Ja11.26, 1915.

4 SHEETSSHEET Z.

SCALE Witnesses W 5 Zilii J. BECKER.

COPYING 0R BNLARGING CAMERA.

APPLIOATIOH FILED NOV. 3, 1914.

Patented Jan. 26, 1915.

4 SHEETS-SHEET 3.

Inventor W 8% m M o E L m mo 3 v m W. V m J V w v m H 6 1 w, m m J m W?h. m a m a Q a x 2 \fi e w qfi m\ r k J. BECKER.

COPYING 0R ENLARGING CAMERA. APPLICATION FILED Nov. 3, 1914.

Patented Jan. 26, 1915.

J0 ll BD =\/ma"-FN 29 1 1| =v 50 -30 In ventor JOSEPH BECKER, OFWASHINGTON, DISTRICT OF COLUMBIA;

COPYING 0R ENLARGING GAHERA.

Specification .of Letters Patent.

Patented Jan. 26, 1915.

Continuation ct application Serial No. 285,802,-fi1ed November 4, 1905.Thisapplication filed November 3,

1914; Serial Ho. 870,066:

To all whom it may concern:

Be it known that I, JOSEPH BECKER, a citi is filed as a continuation ofmy earlier. ap-

plication for patent on photographic carneras, Case L, filed November4:, 1905, Serlal N 0. 285,802; being the same in substance as suchearlier application, with certain desirable additions.

My invention relates to copying or enlarging cameras of the type inwhich the two end frames, that is to say, the support for the objectplane and the support for the image receiving plane, are respectivelypivoted on the diametral lines where such two planes are met by ameridianal plane of the lens; this being done to permit of tilting thesaid two end frames toward each other to produce desired changes in theshape of the projected image.

It is well known that a negative which was inclined to the verticalduring exposure in the taking camera is distorted so as to show allvertical lines of buildings,.etc., as converging or diverging instead ofparallel, and that the parallelism of these vertical lines may berecovered by copying or reproducing from the distorted negative in acopying or enlarging camera ofthe type referred to. The process,however, is diflicult to apply so as to secure the best attainableresults, because if one frame be inclined to secure parallelism, theother frame will have to be inclined to recover the sharpness of focuslost in inclining the first frame, and this inclination of the secondframe redeforms the image. The problem is further complicated by thefact that the -relation between corresponding inclinations of the twoend frames must change when any change is to be made in the size of theimage.

One object of my invention is to provide mechanismthat shall compel thetwo pivoted end frames to tilt. simultaneously toward each other inaccordance with correct-optical principles so that the operator needonly British Patents tilt one of the frames either directly or by meansof'the mechanism in order that the other frame shall simultaneously turnin the manner and degree required to keep all parts of the imageuniforinlysharp, if the image was sharp when the end frames wereparallel; and a further object of my invention is to provide end frametilting means adapted to cooperate with and not interfere with theoperation of automatic focusing mechanism such as disclosed, forinstance, in my 24,292 of 1911 or 29,701'of 1912, in order to keep allparts of the projected image sharply in focus at all inclinations of theframes and for all extensions of the camera.

In the accompanying drawings, which are made to scale in allessential-particulars: Figure 1 is a plan of a copying or enlargingcamera provided with my tilting mechanism in its theoretically exactform, the end frames being inparallel relation and mounted to tilt ondiametral axes P, P that are vertical. Fig. 2 is a similar view of thesame camera with the end frames in a tilted relation. Fig. 3 is anelevation, with parts broken away for clearness, showing a simplifiedform of my tilting gear in combination with focusing linkage of the formshown in Figs. 7 to- 12 of my said British Patent 24292/11, the endframes being mounted to tilt on diametrial axes P, P that arehorizontal. Fig. 4' is a diagram illustrating the geometrical principlesinvolved in Fig. 3 and generally in all forms of the invention. Fig. 5shows a distorted negative. Fig. 6 shows its corrected and enlargedreproduction as made in the camera of Fig. 3. Figs. 7 to 9 show pin holecameras used to illustrate the principles of photographic perspective.Fig. 10 is a plan view of a combination similar to that of Fig. 3,

- but comprising the preferred type of focusing camera and gear shown inFigs. 17 and 19 to 22 of my said British Patent 24292/11, and having thediametraltilt axes P and P vertical as in Fig. 1. Fig. 11 shows amodified form of the tilting lever of Fig. 10.

Theory of inclined images.My tilting gear-must necessarily act to tiltthe end.

frames in accordance with the, law governing the image formation ofinclined planes.

ioo

- Patent 24292/11.

This law may be established as follows: Let P and P, Fig. 4, be any twoconjugate foci on the principal axis of the lens 99, which has itsnodalpoints at N and N, and its rincipal fo'ci at F and F determinin a ocallength FN, e ual NF, equal f. he conjugate foci P an P may have anypositions determined by Newtons formula.

which is given as etk uation 4 of my British his equation may be writtenin the form Dividing both terms by the product f.PN.PN, we obtain whichis the standard lens formula for full conjugate distances PN and NP heredirectly derived from Newtons formula to show that the two formulae areexact mathematical equivalents. These formulae have been followed inmaking the drawings, as may be verified with the aid of the scales shownon the various sheets. In Fig. 4 unof the object space in points V andT, respectively. Any rays PN, QN, RN and VN converging at the nodalpoint N, in the object space, will emerge in the image space Withoutchange of'direction; but they will all be offset so as to diverge fromthe nodal point N. On the other hand, all rays PT,

QT, RT, and VT, being finally merged in the one ray VT of the objectspace, will produce the common emergent ray TQ which proceeds with NJparallel to VN be cause -V is a focal point of the principal focal planeF. This common ray T Q produced-meets the group of rays diverging from Nin the image points R, P, Q, and V the latter, V, being at infinity,doesnot appear in Fi 4. Plane Q PR is, therefore, the im e of plane QPR;a fact which becomes still more evident by noting that point T is simplythe image of point The inclinations of these two conjugate planes QR, QRout of their-normal or parallel relation are measured by the angles NTPand N 'TP' or a and'a', which they form with the principal planes NT, NTof' the lens. By inspection of Fig. 4 it is seen that tan. G=E NT alsothat I NIP! 178,11. 0. -N,,1T,

Y whence tan. a NP tan. a NP This equation 3 is fundamental-and leads tothe following theorem:

The inclinations of conjugate inclined planes, as measured by thetangents of the angles of I inclination, are proportional to thedistances NP and NP of the central conjugate points P and P from theirrespective nodal points N and N.

Now let the object plane QR of Fig. 4 contain a distorted negative whichis shown in Fig. 5 as it would appear to an observer looking in thedirection of arrow 300, Fig. 4, and which has lines WX, QR and YZconverging in a point V situated in the principal focal plane FV of -thelens in Fig. 4. Then Fig. 6 shows the enlarged sharply focused andstraightened out positive WXYZ to be seen in the image plane QR bylookingin the direction of arrow 301, Fig. 4. p

Point V, being located in'the principal focal plane FV, Fig. 4, is thefocus of parallel rays. such as TQ and N'J, so that the image V of Vmust be situated at lower infinity in Figs. 4 and 6 and this explainswhy the three lines W 'X, QR and XY of the positive, Fig. 6, must beparallel;

The image diameter EG, Fig; 6, that lies in the axis P of Fig. 4, andthe object diameter EG, Fig. 5, that lies in the axis P of Fig. 4, areconjugate focal lines'perpendicular to the paper in Fig. 4, and theirlengths (of 16 and 24 centimeters, respectively) are proportional to theconjugate distances NP and NP. We, therefore, have where 'n, designateseither the value of the copying factor as measured along the tilt axes Pand P; or, the scale-of reproduction for all lines of the object whenthe end planes QR and QR are in their normal position perpendicular tothe lens axis FF.

Combining the results of equations 3 and 4, we finally obtain tan. a N Ptan. a T NP Tangent tilter, Figs. 1 and 2.The principle involved inequation 3 is embodied in my tangent tilter, Figs. 1 and 2, where 400,401 are the rails of a bench upon which is rigidly mounted the lensframe L carrying a lens 99, the nodal and focal points of which are,respectively, indicated by dots N, N and F, F. On the same benchareadapted to slide a carriage 402 and a carriage 402. On carriage 402 ispivotally mounted the object frame 0, whose vertical diametral axis ofrotation is indicated by a dot P. This frame 0 has an arm 403 slottedperpendicularly to the frame to admit a pin 27 which is mounted on a bar404 guided in a dovetail groove of carriage 402 to slide transversely ofthe carriage 402. The image frame I is similarly mounted on carriage402; its vertical diametral axis of rotation being P; its slotted arm403; its traversing pin p; and its traversing bar 404'. The distance PH,Fig. 2, from axis P to the path of pin 79, and the distance PH, Fig. 2,from axis P to the path of pin 70, may be of any length desired, butthey should be equal as shown so that the pins 7) and 7? shall movealong-the tangents of arcs having the same radius.

The motions of pins p, p and of their bars 404, 404 are controlledthrough pins 5, b by a slotted lever 410 pivoted at 0 on a bar 411 whichis rigidly clamped to the bench by a bolt 412 which passes freelythrough bar 411 and screws into an enlarged clamp nut 413.

The distance 0K, Fig. 2, from fulcrum c to the path of pin 6 shouldequal NP; and

I the distance 0K, Fig. 2, from fulcrum 0 to the path of pin 6 shouldequal NP. To facilitate the determination of these distances the lever410 is preferably graduated as shown from the fulcrum 0 as zero point ineither direction. In. Fig. 1, for instance, where 06 and 0b are,respectively, equal to 0K and 0K of Fig. 2, itis seen that a?) and NPare both equal to 50 centimeters; while 0?) and NP are both equal to 75centimeters.

The three pins 6, c, I) might be shifted to I the right or to the leftwithout changing their tilting efiect on the end frames, provided thespecified equality of 0K and 0K to NP and N 'P be preserved. In Fig. 1'

pin 12' is with the p ,between pins 6 and b,

not be in alinement with its corresponding pi-n p, but must be offset adistance d, Fig. 1, equal to the internodal distance NN.

To permit of making the offset d exactly equal to any given internodalspace NN, the traversing bar 404 is divided into two parts 404 and 414having feet 415 and 416 which are clamped together by screws 417. Thesescrews 417 screw into foot 415 and pass freely through a longitudinalslot formed in foot 416. The latter is provided with an index mark orarrow head 418 to indicate the degree of offset on a scale which isgraduated on foot 415. This scale runs from the zero point five spacesto the right for internodal spaces NN that are positive;

and it runs from the same zero point five spaces to the left forinternodal spaces NN that are negative. A Vernier scale might besubstituted for the plain scale shown, as readily understood.

The lens shown, lens 99, has a focal length FN or N 'F of 30 centimetersand a relatively large internodal space NN of plus 4 centimeters, thelatter being selected relatively large for clearness. The exactstructural conditions which are all satisfied in Figs. 1 and 2 may besummed up in the three following equations.

Constant d :NN' 4 cm. (6) Variable 0K :NP :50 cm. (7) Variable 0K=NP=75cm. (8)

right infinity, and the image frame I in focus on left infinity, so thatP and P shall, respectively, coincide with the principal foci F and F ofthe lens. Thirdly. Set and clamp bar 411 to bed 400, 401 so as to holdthe fulcrum point 0 exactly midway The carriages 402 and 402 may now beseparated to permit of setting the end frame axes P and P in focus oneach other and the device is ready for use.

I With lever 410 held parallel to the lens axis as-in Fig. 1, the endframes 0, I may be moved toward and away from the lens 99 to focus forany desired scale of reproduction as'freely as if the tilting mechanismwere not present. Moreover, any motions of P and P are also communicatedto b and b, respectively, so that the lever arms ab and 0b are variedautomatically in such manner as to remain constantly equal to thevarying distances PN and PN.

Rocking lever 410, as in Fig. 2, therefore, moves pins p, p throughdistances Hp and H'p', respectively, equal to distances Kb and Kb andexactly proportional to the distances PN and N 'P', whatever thesetances may happen to be; and, as the pms p, p move along tangents toarcs of equal radius PH and P'H', Fig. 2, the end frames are tiltedexactly as required by equation 3, which is observed in all relativepositions of the frames, even when the axes P and P are not in focus oneach other; that is to say, even when points P and P are not located soas to satisfy equation 1 and lts equivalent equation 2,-but if thecamera 1s properly focused with its end frames parallel so as to satisfyequation 1 and its equlvalent equation 2, then all parts of the imagewill be and remain in focus when the end frames are tilted by rockingthe lever 410.

The focusing of the end frames in their parallel relation may be donewith a ground glass in the ordinary manner, or by computation, or by afocusing scale, or preferably by means of automatic focusing mechanismsuch as the linkage focuser of my Britlsh Patent, 24292/11 or the radialcam focuser of my British Patent 29701/12.

Complete form, Fig. 3.'A complete combination of focusing and tilt gearis shown in Fig. 3, where the camera proper and linkage are thoseillustrated in Figs. 7 to 12 of my said British Patent 24292/11, andwhere the tilting gear is of simpler form than that of my presentFig. 1. The simplicity is secured at the cost of accuracy; but the lossin accuracy is not appreciable if the device 1 be used within prescribedlimits.

The bench 100, slideway 102, carriages 103', 104, pin 111', bearings112, 113, bolts 115, 117, and the linkage ABA D or 120, 121, 122 and 123are all substantially as shown in Figs. 1 to 12 of my saidBritish Patent24292/11; but blocks 105, 108 and 109 are slightly modified to providefor pivoting the end frames. To facilitate comparison with 1 change theinclination of the tilt lever 218, if. the tilt lever happens to lieparallel with present Figs. 1 and 2 the lens used is the same lens 99and the frames used are the same frames 0, L, I shown set and tiltedexactly as in Fig. 2; but the frames are here identified as O, L, I.

The object frame 0' has trunnions, such as 210, by which it is mountedto swing beand wrist pin 12" forming a crankarm P'p' of the same lengthas Pp. These crank arms Pp and Pp' are connected to turn simultaneouslyin opposite directions by a slotted lever 218 which is fulcrumed on thelens frame L by means of a stud a mounted on a bracket 220. This bracketis adjustably together as freely as if they were rigidly mounted on thecarriages 103, 104, and not connected by tilting gear. The apparatuswith its frames in such parallel rela-' tion is, therefore, firstadjusted in the manner set forth in my said- British Patent 24292/11, sothat the Newtonian or constant product space elements DA, DA .of thelinkage shall always equal the Newtonian distances FP, FP of the lens.The carriages 103, 104- are then moved into the position where the s aceelements DA and DA are equal; and nally pin 0 is set and clamped midwaybetween the wrist pins p and p. By this adjustment the lever arms 0;)and 0p in the normal position are made equal to what they should be fora lens that has its two nodal points N and N coincident; and

they act to turn the crank arms Pp and Pp' through angles whose sines,proportionally represented by 39S and pS', Fig. 3, vary approximately inaccordance with the law laid down above for the tangents, proportionallyrepresented by pH, pH, Fig. 2. This simplified form of tilter, Fig. 3,may, therefore, be designated as the sine tilter, whereas thetheoretically correct form of Figs. 1 and 2 may be designated as thetangent tilter..

Actuating the linkage 120123 does not the slideway, in which positionthe lever lever 218 is in inclined position the two end frames are alsoinclined, and at least two of these three inclinations will be changedby any actuation of the linkage 120-.-123, as required in view ofequation 5 by the changes produced in the copying factor a. If theoperator, therefore, takes hold of one of the end frames and slides italong or tilts it in any manner, the focusing mechanism (which nowconsists in the combination of the linkage 120123with the tilt lever118) will simultaneously displace the other frame longitudinally andangularly in the manner and degree required to keep all points of the 603, however, is shown as acting correctly to image atall times sharply infocus; that is to say, the image and all partsthereof will always remainin focus, and no motion permitted by the mechanism can throw any pointof the image out of focus. The middle horizontal line of the image is,kept in focus by the linkage 120-423 alone, but the top and bottom partsof the image are focused at all times and in all positions by thecooperation of the linkage with the tilt lever.

Second complete form, Fig. 10.-The camera of Fig. 3 has the advantage ofbeing well suited for illustrating and disclosing the principlesinvolved, but it is not the preferred practical form, because thelinkage ABA shown produces side pressures that increasefriction. In thepreferred form, Fig. .0, I use a camera of the type illustrated in Figs.19 to 22 of my said British Patent 24292/11 in combination with the verysmoothly working linkage shown in Fig.1? of the same patent and the tiltaxes P, P are made vertical as in present-Fig. 1.

The bed, in Fig. 10, comprises two parallel rails 600, 601, connected attheir middle by a crossbar 602, which supports the lens pintle D athorizontal distances FD and FD from the principal focal planes F and Fof the lens. The object frame pintle A is connected at a horizontaldistance PA, equal to FD, from the vertical pivotal axis P, of theobject frame 0, by means of a rigid, but adjustable, connectioncomprising the carriage 603, block 604, clamp bolt 605, and bracket 606.The image frame pintle A is similarly connected at a horizontal distancePA, equal to F D, from the vertical pivotal axis P. of the image frameI", by

means of a rigid, but adjustable, connection, comprising the carriage603, block 604, clamp bolt 605 and bracket 606. The three pintles A, D,A are connected by my preferred form of focusing linkage which iscomposed of two equal short links DB and .DB, and of four equal longlinks AB,

AB, AB and AB' The two short links are adjustable to permit ofmakingtheir length BD equal to the square root of the difference betweenthe squares of the long link length AB and the focal length FN. Thetilting gear comprises equal crank arms Pp and Pg) connected by aslotted lever 618, having its fulcrum c adjustably mounted on the lensframe L by bracket 620 andscrews 621. The ratio Pp/FN of crank armlength to the focal length is 20 to 30 in Fig. 10, and 21 to 30 in Fig.3, so that the two tilting gears are substantially alike in everyparticular. The gear of Fig.

make the image plane meet the nodal plane N at T directly opposite T, aswould be the case if the tangent tilter of Fig. 1 were L slne tilterdoes act almost correctly; whereas, the camera of Fig. 10 is set forcopying factor n equal 1.2, at whichscale the same gear must produce theappreciable ofi'set TT shown.

In Fig. 10, which was planned so as ,to avoid fractional values of thescale annexed thereto, the three adjustable dimensions of the focusinggear are PA, PA and BD, and their values are, respectively, 41 cm., 22cm. and 40 cm., as indicated in the equations noted on the drawing closeby Fig. 10. In practice these three dimensions are determinedautomatically, without measurement so that fractional values are aseasily taken care of as any others; thus: dimension PA is determinedautomatically by bringing A into coincidence with D and focusing theobject frame 0 on right infinity; similarly, dimension PA isdetermined-automatically by bringing A into coincidence with D andfocusing the image frame I on left infinity; finally, dimension BD andits equal DB are determined automatically, after the determination ofdimensions PA and PA, by setting the object frame 0 and the image frameI in focus on each other.

After the focusing mechanism has been fully adjusted and regulated asjust explained with the end frames in parallel relation, the focusinggear ADA is set to make distances AD and DAequal to each other, and thenthe. fulcrum 0 of the tilt lever is set and clamped exactly half waybetween pins 72 and p, as previously explained' in connection with Fig.3.

The tilt lever 618 of Fig. 10 may in certain cases preferably be made asin Fig. 11, where the modified form of lever 718 has .pivotal connectionwith the end frame pintle negative, 'Fig. 5, in the object frame 0' sothat its middle vertical PV shall be per pendicular to the horizontaltilt axis P, and then, going back to the image frame I, he tilts theframes in the direction and to the extent required to make the images ofthe verticals WX and YZ exactly parallel. Parallelism is easilydetermined by means of a pair of dividers or by means of a graduatedrule. When parallelism is secured,'it will befound, as already provedabove, that the vanishing point V has been brought into the nearerprincipal focal plane F, as shown in Figs. 3 and 4, such focal planebeing considered as extendin all the way to infinity if necessary to mae the rule general. Thus the perpendicular distance FV is and should beinfinite when the verticals WX, YZ of the negative are parallel.

C'orrect perspe'ctioa-In the majority of cases parallelism of theverticals is all that the operator desires. By mounting the negative inframe 0, however, to make the vertical distance FV either longer orshorter than shown in Figs. 3 and 4, and the angle a correspondinglysmaller or larger, the operator can secure differences in the relativelength of the rectangular image, Fig. 6. In Fig. 6 the length WX shownis 30 cm. and the width XZ is 24 cm. so that the relative length orratio of length to width is 30/24, or 5/4. It is this ratio that canthus be varied, and only one of thev difi'erent reproducible proportionsof the rectangular image will correspond to the correct perspective thatwould have been obtained if the negative had been held exactly verticalduring the exposure. I have discovered the novel principle that thiscorrect perspective is. obtained when the distance NV or h", Fig. 4, hasa certain value, as will presently be explained with the aid of the pinhole cameras shown in Figs. 7. and 8.

Questions of photographic perspective are most easily treated by meansof pin hole cameras because the pin hole of such cameras may beconsidered as a lens that is perfectly rectilinear and always in focus,and that has its two nodal points N and N coincident in one pointassingle center of perspective.

In glass lenses the nodal points hardly ever coincide, but the sameperspective principles apply, becausethe internodal space of the lenssimply produces a relative shift or translation of the object and imagespaces, or of the incident and emergent parts of the diagram withoutintroducing any changes in direction, shape or size.

In Fig. 7, 500 is a common pin hole camera with its pin hole at M andshowing how the camera was held during exposure to produce a negative501 of a small vertical wall 502, the axis PM of the camera being aimeddirectly at the central point P 'of the wall. The height of this wall502 is 80 cm. and the unseen uniform width is supposed to be 64 cm., sothat its-height is 80/64, or five-fourths (5/4) of the width. Accordingto the known rules of perspective, the negative 501 will show allverticals of the wall as vanishing in the point V (Fig. 7 where theproduced plane of the sensitized surface on plate 501 is met by thevertical or plumb line MV drawn through the pin hole M. The exactoutline of the distorted picture obtained is shown in Fig. 5, where thehorizontal diameter EPG is 16 cm. long. If a tilt back had been used toturn the plate on the horizontal axis P into the vertical dottedposition 503, the picture 9P1" thus obtained would be free fromdistortion; that is to say, it would be rectangular, 16 cm. wide and 5/4of 16, or 20 cm. high. This correct negative is a vertical section ofthe rays emerging from the pin hole M. Any other vertical section QPR',Fig. 7, of the incidental parts of the same rays throng M produces acorrect perspective such a desired in making the copy or enlargementshown in Fig. 6, where the width EG is 24 cm. and the height Q'R' is 5/4of 24, or

Now let the distorted negative 501 be set and held in front of anenlarging pin hole camera 510, Fig. 8, at any distance and in anydesired position, but so that its vanishing point V shall be situatedsomewhere on the are 513 of a circle drawn about the pin hole M ascenter with a radius 'M' V or is equal to the vertical distance MV, ork, in the taking camera, Fig. 7; and .let a screen 511, Fig. 8, be setand held in any desired position 511 or 512 inside of the camera 510,but parallel to the radius 71., then the pro jected image QPR' or Q"'P"Rso obtained will be similar to the correct perspective Q'PR' of Fig. 7,as will now be proved.

Any correct perspective Q P R in Fig. 7

is evidently similar to the correct vertical negative 9P1, and theheight gr of this negative is twice the height of the linear element Pr.The similar triangles PrR and VMR yield 1 RP PT=7L EV All images such asQ/P'B and Q,"P"R' obtained in Fig. 8 are evidently similar to each otherand to the perspective g'Pr that is obtained by drawing a plane 9'?through P parallel to the radius 72.. The horizontal diameter P of thisimage gr', Fig. 8, is identical with the common horizontal diameter P ofimages qr and QB in Fig. 7, and this, in view of Fig.5, is 16cm. long.

In'Fig. 8, the pin holeM' and all lines of the negative 501, convergingin V, determine planes intersecting on the vertical line it, and,therefore, these planes must meet the plane gr, which is parallel to it,along lines that are parallel so that the image 9'1" has all of itshorizontal diameters equal, or

16 cm. long.

The similar triangles Pr'R and VMR yield RP av Dividing equation 9, termfor term by Pr h (10) equation 10, we obtain It could similarly be shownthat any other corresponding height elements in Fig.

gr of Fig. 8 is in all respects the exact duplicate of the 16 by 20centimeter image or of Fig. I Fig. 8 is very different from thecorresponding angle PV M or z of Fig. 7. The relative height QR'/E'G'obtained in the final image, Fig. 6, is, therefore, simply proportionalto the length h, Fig. -8, or h, Fig. 4, and this principle is entirelyindependent of differences that may exist between the focal length ofthe lens in the taking camera, Fig. 7, and the focal length of the lensin the copying or enlarging camera, Fig. 4.

The distance it in the taking camera maybe calculated by noting that his the hypotenuse of the right angled-triangle VPM,

in which the two sides VP and PM are easily measured, PM being the depthof the camera during exposure, and VP the directly measurable distancefrom the central point P of the negative to the vanishing point V.

The angle PVM or i in Fig.7 is equal to the inclination of the takingcamera 500 during exposure, so that if this inclination has been notedwe can, after simply meas-' uring PV on the finished negative, calculateh by the formula h PV. sec. z (12) The distance it" in Fig. 4 isnecessarily longer than the focal length FN of the lens 99 so thatcorrect perspective can only be recovered by using. a reproducing lens99 whose focal length is shorter than the vertical distance it in Fig. 7

The above exposition leads to the three following simple rules, whichare all that the practical operator need remember.

Rule 1: To recover parallelism of verticals converging in a point V ofthe negative, in-

7, although the angle PVM ofcline the negative so as to bring V into thenearer focal plane of the lens.

Rule 2: well as parallelism, follow Rule 1, shifting the negativetoincrease or decrease the vertical distance FV, Fig. 4, so as to make theinclined distance h" in the enlarging camera, Fig. 4, equal to what thevertical distance 72. was in the taking camera, Fig. 7.

Rule 3: A reproducing lens having a focal length equal to or greaterthan k in Fig. 7 cannot be used to recover correct per- To recovercorrect perspective, as

spective, but it will still answer to secure parallelism of theverticals under Rule 1.

Short focus taking and reproducing Zens.

Where the focal length of the taking lens M, Fig. 7, is so short thatvariations in the depth PM of the camera due to focusing are nil ornegligible asin the smaller socalled fixedfocus hand cameras, there is aspecial advantage in using the same lens larglng camera, because thefocallength FN, Fig. 4', and the depthPM, Fig. 7, then- VPM of Fig. 7;Angle i of Fig. 7 and.

7 and Fig 8 are equalaand that the image .5 as reproducing lens in thopyin or en-..

angle a of Fig. 4 are then equal to each other and to the inclination aof the image frame I, Fig. 4. As the line VP of the negative, Fig. 7,'isthen equal to the vertical VF in the enlarger, Fig. 3, it must beshorter than the hypotenuse VP, Fig. 3; and, therefore, the center P ofthe, negative must be shifted in plane PT, Fig. 3, toward T throughthehypotenuse excess (VP-VF),

Fig. 3, to bring the vanishing point V of the negative into coincidencewith V of Fig. 3. lVhere the copying factor n is large, as usualwithfsmall negatives, the distance PF, Fig. 3, is relatively short andthe shift or hypotenuse excess (VP-VF), Fig. 3, is so small as to becomenegligible. If, therefore, we neglect the slight shift required inpractice, from P toward T, Fig. 3, to bring the vanishing point of thenegative, under Rule 1, into the focal plane F in exact coincidence withV, all rules for securing a sufliciently correct imageare reduced to thefollowing simple Rule 4: To secure a practically correct perspective,where the taking lens. is -of short focal length and is used asenlarging lens, set the image frame I of the enlarger to make itsinclination a, Fig. 3, equal to the inclination-i of the taking camera,Fig. 7.

A small hand camera with automatic means for recording its inclinationdirectly on the negative at the moment'of exposure is, therefore, thenatural complement of-my 3 present invention.

Indirect adoantages.-My invention has several indirect advantages thatare probably of greater value and importance than its direct advantage.The direct advantage of the invention is that it permits of taking adistorted negative to make therefrom, very easily, positives, or evenother negatives, of any desired size and showing no trace of distortion. Distorted negatives in present practice, however, are onlyproduced in the rare instances where their production is unavoidable, aswhere the swing back and rising front of the taking camera have reachedthe limits of their adjustments and would have to be moved farther tosecure full correction.

The operator who has a copying or enlarging camera with combined tiltand focusing gear such as shown in Fig. 3 corrects distortion so easilyat any desired scale of reproduction that he need never make any eifortsto avoid it. With him distortion will be the rule instead of theexception, because distorted negatives are more easily produced and arebetter in all other respects than correct negatives made under the sameconditions with rising front or swing back. Suppression of the risingfront and of the swing back and of the level, and of the troubleinvolved in the use of such devices not only simplifies the constructionand manipulation of the taking camera, but

- it results in a higher optical and image producing efliciency of suchcamera as will now be explained.

Disadvantages of the swing back-1f the sensitized plate 501, Fig. 7, ismounted to turn in the camera box 500 on a horizontal axis P, the camerais virtually provided with what is known as a swing back. The

swing back serves mainly to turn the plate 501 back into the verticalposition 503.to avoid distortion whenever the camera cannot take in the,whole of the object to be photographed without being pointed downwardlyas shown in Fig. 7 or upwardly as would be the case in Fig. 7 reversed.

If M were a glass lens its nodal plane MT would be met in T by thevertical plane of V the object 502 to be photographed; and, in

accordance with equation 3 and Fig. i, the camera plate 501 to be infocus at all points should be turned clockwise to fall in with line PT'.With the plate 501 in its normal or full line position the operator,therefore,

has two alternatives; he may, first, tilt the upper edge of'the plateslightly toward the ob ect to improve focus, and he may, sec-.

camera of Fig. 7 with 1ts plate in the normal full line position 501.

Disadvantages of the rising f1'0nt.If the lens M, Fig. 9, be mounted-ina board 516 that slides vertically across the front end of the camerabox 515, while the sensitized plate 517 remains normal and vertical, thecamera is provided with what is known as a rising I front, which is usedfor the same purposes as the swing back. In Fig. 9 it is shown droppedas it would have to be if the camera of Fig. 9 were substituted in Fig.7 to produce the same correct perspective qPr. That is to say, points MP and 1'" of Fig. 9 are exactly superposable with the correspondingpoints M, g, P- and 1' of Fig. 7.

If M of Fig. 9 were a glass lens, its principal axis would meet theplate 517 near the lower edge, at em, showing that normally discardedand poorly acting marginal rays, such as M" g", are brought into use andthat the many highly desirable rays which pass just below center m arediscarded. Here again, as with the swing back, passable sharpness canonly be secured by reducing the effective aperture and speed of thelens.

Rising front and tilt back combined-It is seen that the rising front,Fig. 9, shifts a valuable part of the lens field off the sensitizedplate 517 to bring into use poorly acting and usually discarded marginalrays; that the tilt back inclines the plate 503, Fig. 7, on the lensaxis MP so that only one horizontal line of the plate can be sharplyfocused at a time; that these different disadvantages of rising frontand swing back are not mutually compensatedby the combined use of risingfront and tilt back; finally, that both rising front and tilt backinvolve the use of levels, of reduced lens aperture and of prolongedexposure only to produce negatives that are not as uniformly sharp asthey might be. It is, therefore, better, on the whole, to make cameraswith a solidly mounted lens, without swing back, without rising front,and without levels, to be aimed, like a gun, directly at the object tobe photographed, and producing distorted but uniformly sharp and quicklyexposed negatives, which are easily corrected in my tilting copier orenlarger.

, v with the common lenses 9; Note 2: In Fig. 1 and in Fig. 3 I haveGeneral remarks.

' shown the tilting lever as pivoted on its fulcrum pin 0, but, ifpreferred, it might in either of these figures, as in Fig. 10, bepivoted on one of the wrist pins instead and have sliding connectionswith the fulcrum as well as with the other pin.

Note 3: Where the inclinations of the end frames are small, as incorrecting slight er-' spective distortions, the sine tilter of Figs. 3and is in all cases nearly as accurate as the tangent tilter of Fig. 1,because the sine and the tangent of a small angle are substantiallyidentical.

Note 4: A given sine tilter will produce inclinations of the image frameas large as half a right angle that are substantially correct when thecamera is set to copy at a certain scale n equal n"; but that areexcessive or deficient accordingly as the camera copies at scales nthat'are respectively greater or less than a; the value of n" being given bythe sufficiently accurate empyrical formula copying factor n" of bestperformance must be (1+0.7 0.7), or 1, 19. That is to say,

. when the camera of Fig. 3 is set asin such figure to copy one andone-half times actual size, the end frames are tilted substantially asrequired by theory even for inclinations of the image frame as large as415 degrees; but Where the copying factor n is 3 the inclination of theimage frame, if large, is excessive; and where thecopying factor n is lthe inclination of the image frame, if large, is too small. An instance.of such deficient inclination is shown in Fig. 10, Where the tiltinggear is substantially the same as in Fig. 3, but the camera is set forcopying factor at equal 1.2 or 6/5. In all cases, therefore, where thecontemplated range of variations in the values of the copying factor nand of the end frame inclinations a and a is large it is preferable touse atangent tilter,-such as that of Fig. 1. The-substitution of atangent tilter for the sine tilter in either Fig. 3 or Fig. 10 presentsI no mechanical difficulties.

Note 5: If the lens 15 specially designed for .the exclusive use of .acertain group of actinic re s, or if it has a so-called chemical focus,all adjustments of the focusing mechanism should be made for suchactinic .or chemical rays, as will readily be understood.

Note 6: A mathematical equivalent of my equation 3 is found in theformula tan. a= Xtan. a, (14) which was published by Ca tain Scheimpflug in the Photographisc e Correspondenz, Vienna, 1898 (p. 118, Fig. 5on page 119, and erratum on p. 221).

A mathematical equivalent of my equations 3 and 5 is found in theformula tan. a a. tan. a (15) elements NP and NT which I directlyutilizeas the automatically varying lever arms of my tilt lever.

What I claim as, my invention and desire to secure by Letters Patent is:i

1. The combination with an enlarging or copying camera comprising alense frame, and two end frames mounted to rotate on parallel axes; ofarms rigidly connected with said three frames, and a lever adapted toact on said arms to revolve the said end frames simultaneously inopposite directions.

2. The combination with a copying or enlarging camera comprising a lensframe and two end frames mounted to rotate on axes that .are paralleland adjustable to vary their distances from the nodal or principalplanes of the lens; of mechanism connecting said end frames and adaptedto cause them to revolve simultaneously in opposite directions.

3. The combinationwith a copying or enlarging camera comprising a lensframe and two end frames respectively mounted to rotate on parallel axesof their focal planes, such axes being adjustable in position to permitof setting them in difierent conjugate relations to the lens forsecuring an axial image on theone axis bearing different desiredproportions to the axial original on the other axis; of mechanismconnecting said end frames and adapted to cause them to revolve inopposite directions.

4. The combination with an enlarging or copying camera comprising a lensframe, and twoend frames mounted to rotate on parallel axes, of a leverhaving its fulcrum copying camera comprising a lens frame,

and two end frames mounted to rotate on parallel axes, of automaticfocusing gear to change the copying factor or size of the image; andtilting mechanism to change the shape of the image, said tiltingmechanism being adapted'to permit the free actlon of the focusing gear.

7. The combination with an enlarging or copying camera having a lensframe, and two end frames mounted torotate on parallel axes, ofautomatic focusing gear to change the copying factor or size of theimage; and tilting mechanism to change the shape of the image, saidtilting mechanism having pin and slot engagement with two of the saidframes to provlde for automatically changing the velocity ratio oftransmission as required when changes are made in the said copyingfactor by operation of the said focusing ear. p

8. The combination with an enlarging or copying camera having a lensframe, and two end frames counted to rotate on parallel axes, ofautomatic focusing gear to change the co ying factor or size of theimage; and ti ting mechanism to change the shape of the image, saidtilting mechanism havin pin and slot engagement with the two en framesto provide for automatically changing the velocity ratio of transmissionas required when changes are made in the said copying factor by'operation of the said focusing gear.

9. The combination with an enlarging or copying camera comprising a lensframe, and two end frames mounted to rotate on parallel axes of theirrespective focal planes; of a support for thelens frame and supports forthe pivotal axes of the said end frames, one of said end frames havingan arm extending perpendicularly from its axis and focal plane towardthe lens; and the other end frame having a similar perpendicular armextending away from the lens; and a lever adapted to mechanicallyconnect substantially corresponding points of the said two perpendiculararms; the fulcrum of said lever being mounted on the said lens frame ata point which divides said connecting lever into effective IBVQF.

arms substantially equal to the corresponding distances of thenodal-points of the lens from the said pivotal axes.-

10. The combination with an enlarging or copying camera comprising alens frame, and two end frames mounted to rotate on parallel axes oftheir respective focal planes;

of a, support for the lens frame and supports for the pivotal axes ofthe said end frames, said three supports being adjustable to vary thecopying factor as measured on said pivotal axes; one of said end frameshaving an arm extending perpendicularly from its axis and focal planetoward the lens; and the other end frame having a similar perpendiculararm extending away from the lens; and a lever adapted to mechanicallyconnect substantially corresponding points of the said two perpendiculararms; the fulcrum of said lever being mounted on the said lens frame ata point which divides said connecting lever into effective lever armssubstantially equal to the corresponding distances of the nodal pointsof the lens from the said pivotal axes.

11. The combination with a copying or enlarging camera, having its twoend frames mounted to turn on parallel diametral axes P, P perpendicularto and intersecting the principal axis F, F of the lens mounted in thelens frame; of end frame tilting mechanism comprising two substantiallyequal P, P perpendicular to and intersecting the principal axis F, F ofthe lens mounted in the lens frame; of end frame tilting mechamsmcomprising two substantially equal crank arms extending perpendicularlyand in the same direction away from the said two end framesrespectively, and a tilt lever adapted to act on the two movable ends ofsuch crank arms to tilt the said two end frames in opposite directions,said tilt lever having its fulcrum mounted on the said lens frame; alsomeans to permit of varying the con ugate focal distances PN, PN' of theaxes P, P from the nodal points N, N of the lens, and means forautomatically varying the two lever arms ofithe tilt lever to keep themsubstantially equal to the said varying conjugate distances PN, P'N, re-

P, P perpendicular to and intersecting the principal axis F, F of thelens mounted in the lens frame; of end frame tilting mechaadapted to actonthe twomovable ends of nism comprising two substantially equal crankarms extending perpendicularly and a in the same direction away from thesaid two end frames'respectively, and a tilt lever spectively; and meansfor simultaneously Corrections in Letters PatentNo. 1,126,352

displacing the two diametral axes P and P with relation to the lens inaccordance with Newtons formula, .or equations 1 and 2.

[emu] 14. The combination with a copying or enlarging camera comprisinga lens frame, and two end frames respectively mounted to rotate ondiametral axes of their image planes, such axes being parallel andadjustable to vary their distances from the nodal points of the lens; ofmechanism connecting said end frames and adapted to cause their imageplanes to revolve simultaneousl in opposite directions from thepositions they occupy when parallel or set perpendicularly to the lensaxis, at such rates, for all positions of the said diametral axes, as toalways meet the principal or nodal planes of the lens substantially inconjugate or directly opposite lines.

In testimony whereof, I have signed my name to this specification in thepresence of two subscribing witnesses.

JOSEPH BECKER.

WVitnessesz' MARY E. COWELL, H. P. HOWARD, Jr.

It is hereby certified that in Letters Patent 1,126,352, granted January26, 1915, upon the application of Joseph Becker, of Washington, Districtof Columbia, for an improvement in Copying or Enlarging Cameras, errorsappear in the drawingsand in the printed specificationrequiringcorrection as follows: In the drawings, Fig. 3 FOR 0 READ O; in thespecification, page 2, in the four equations included between lines 70to 90, FOR tan. six times occurring READ tan; page 3, in the equationincluded between lines 6 to 10, FOR tan. twice occurring READ tan; page7, equation 12, FOR sec. READ see; page 9, equations 11 and 15, FOR tan.four times occurring READ tan; page 1, line 22, FOR meridianal READmeridional; page 2, ITALICIZE lines 91 to 96; page 9, line 77, ITALICIZEz; page 9, line 85, FOR Franpaise READ franpaqlse; page 9, line 97, FORlense READ lens; page 10, line 36, FOR counted READ mounted; and thatthe said Letters Patent should be read with these corrections therein,that the same may conform to the record of the case in thePatent'Ofiice.

Signed and sealed this 2nd day of March, A. D." 1915.

J. T. NEWTON, Acting Commissioner of Patents.

